Rubber valve stem



Nov. 4, 1941.

J. G. KREYER RUBBER VALVE STEM Filed May 2, 1939 ATToRNEYS Patented Nov. 4, 1941 oFlFicE i RUBBER VALVE STEM John G. Kreyer, Akron,

Firestone 'lire & Rubber Company. Akron, Ohio, a corporation oi Ohio .Applicationv May 2, 1939, SerialI No. 271,298

2 Claims.

to rubbervalve stems inner tubes of pneumatic This invention relates such as are used on the f tire casings.

The invention is of primary utility in its application to the-valve stems of tires used on certain makes and sizes of agricultural vehicles, especially tractors. These tractors require additional weight to produce adequate driving trac- Within the valve stem the insert isformed with'` tion, said weight conveniently being provided byd llingthe tires of the vehicle with a suitable liquid. In the winter season, at least, said liquid requires to be of a non-freezing nature, and a calcium chloride solution commonly is used because of its low cost and low freezing point. It is characteristic of calcium chloride,however, to have a corrosive effect upon brass, and when used forv the purpose specified it frequently has attacked the brass inserts that contain the valve mechanism in rubber valve stems. As the result of such corrosion, the chemical bond betweenthe metal inserts and the rubber thereabout has been destroyed, and frequently the inserts have been blown entirely out of the rubber stems.

The chief objects of the invention are to provide a valve stem construction of the character mentioned wherein the metal insert will be firmly retained in place against the pressure of liquid within the tire; to provide simple and economical means for retaining the metal insert in place; to provide valve stem insert-retaining means that will resist the corrosive action of liquid within the tire; and to provide valve stem insert-retaining means that will functionmechanically even though the chemical bond between the rubber and the metal insertis destroyed. Other objects will be manifest as the description proceeds.

Briefly stated, the invention in the improved rubber valve stem resides inthe provision of a local region or zone of rubber under compressive stress, which region is concentricwith the axis of the valverstem and circumscribes the metal insert therein. I

f the accompanyingdrawing-z f Figure 1 is a perspective view` lof a stem constituting one embodiment of the invention, and a fragment of inner tube to which. it is attached;

Figure 2 is a diametric section therethrough on a. larger scale, on the line 2-2 of'Figure 3; and

ure 2. f

Referring to the drawing, there is shown a rubber valve'sten' I0 of conventional or pre- Figure 3 is a section on the une 3 3 of Fig- I the valve stem.

Ohio, assignor to The ferred design, which valve stem may be bonded to the usual rubber inner tube iLconcentric with a port or aperture I 2 therein. Mount'ed'within tlie steinv lll positioned at the axis of the stem and has the usual threaded portion 'I4 projecting from -the free end thereof, remote from the tube wall il.

-the usual longitudinal series of circumferential anges i5, l5 that function to provide a mechani-cal interlock of rubber and metal for assist-` ing retaining the insert in the stem. The-in of the rubberveifecting a chemical bond or adhesionvof the rubber to the metal. If this chemicalbond between the rubber and stroyed by reason of the corrosive action of the liquid carried-in the inner tube, the normal mechanical interlock between the anges i5 and the rubber of the stem is not sumcient to retain the insert within the stem against the pressure of the liquid within the inner tube, even when the vehicle upon which the inner tube is mounted is not in use. Within the insert I3 is the 'usual valve mechanism or insides (not shown). The valve stem i0 is formed with the usual base flange I5 that is adhered to the inner tube structure Il, there being a substantial llet at the juncture of the stem and said flange portion I The rubber structure may be formed with a plurality of radial ribs '|l, l1 extending from the ange portion I6 to the body ofthe stem for the purpose of facilitating the escape of air from between the tire rim the inflating ofthe latter.

For putting a local region Aof. the rubber stem I0 under compressive stress, a constricting annular band 20 is employed, said band `encircling the stem just above the flllet at the juncture of the stem and base flange |16,l and also encircling v the insert I3 within the stem .adjacent the inner end of saidinsert.' Preferably the band 20 .is of axially corrugated construction so as to be constrictable, and any y suitable or preferred means may be employed for constricting it about rubber valve stem after the latter is vulcanized, with the result that the annular zone of rubber between the band and the insert is put under compressive stress, and so grips the insert nore iirmly than it otherwise woul The arrangement is sch that corrosion of the outer surface of Vthe insert I3, progressing outis a tubular metal insert I3 that is' metal is deand the inner tube during.

The band 20 is applied to the u The invention is of simple and .economical it is applicable to valve' stems ofy construction, standard construction simply by the addition of the constriction ring, and it achieves the several advantages set out in the foregoing statement of objects.

Modication may parting from theI spirit of the invention, or the scope thereof as dened by the appended claims.

be resortedto without del What is claimed is: Y I l. A rubber-valve stem comprising an axially disposed tubular metal insert therein, said insert being chemically bonded to the rubber by vulcanization, and means locally circumscribing the stem and applying constrictingpressure to the rubber between itself,and said insert, at the 'inner end portion of the latten `as a means for retarding corrosion of the exterior of the insert.

2. A rubber valve stem torinner tubes, said valve stem comprising an axially disposed tubular metal insert therein, said insert being chemically bonded to the rubber by vulcanization. and a metal ring mounted upon the exterior of th'e stem concentrically of the insert adjacent the inner end of the latter, said ring being constricted so as to. maintain the rubber between it and the insert underl compressive stress as a means for retarding'- corrosion of the exterior oi the insert by uid from within the tube.

A JOHN G. KREYER. 

